704 THE HIGHER ANTHROPOIDS 



to the luiiiiaii slanclard. Its oli\ar\ luick-us is nioiv clearly clcliiird ami more 

 complexly coinoluted. As compaix'cl with the oranfi-outaiifi, the dillerencc 

 is strikin<i;, for in this latter species neither oLitline nor convolution shows an 

 ad\anced degree of diflcrentiation. 



In size as well as morphological definition, the chimpanzee occupies an 

 intermediate position between the orang and the gorilla, w hich latter species, 

 for this reason, seems better pro\ided with coordination ot simultaneous 

 movements of head, eye and hand. The physiological expression of these 

 morjihological conditions may be somewhat diHicult to estal^lish, inasmuch 

 as bt)th the orang and the chimpanzee are known to possess very accurate 

 regulation in their oculo-cephalogyric fLinctions. It is probable that the 

 gorilla has not as yet been sufliciently studied by precise scientilic methods to 

 justify a statement concerning the relative degree of its development m this 

 important department oi neural control. Yet, from what is known of this 

 animal's reactions in captivity, it would seem to possess a high degree of 

 specialization m those delicately adjusted movements of the eye and head 

 for the regulation of the hand in movements of extreme precision. \\ hether the 

 gorilla has actually a greater manual deftness, a more ellectual regulation ol 

 thosecomplementary movements in theeye, the headand the hand which prac- 

 tically welds these parts into a single organ ( in the physiological sense at least) 

 must await still lurther examination bearing upon the comparative behavior 

 of these three primates. The measurabU' dillerences of the mierior oli\arv 

 nucleus are show n in the jjlanimetric coellnu'iits ot t he inlenor olivary nucleus 

 for orang, chimpanzcx" and gorilla as arranged in the follow ing tabulation: 

 Planimetkic Coefficients of the Infekiok Olive in tficHEK Anthkoi'oids 



